Like a real cloud, a hybrid cloud is an amorphous thing. The IT world clearly defines private clouds, and the public cloud is equally clear. However, a hybrid occupies the great space in the middle. In this way, a hybrid cloud is as much a mindset as it is an IT strategy. There's no right way to build a hybrid cloud: it just is.
The nature of a public cloud is relatively clear. When a company takes an application and moves it off-site to another company's servers that are shared with other organizations, it's using the public cloud. Public clouds can do just about anything. However, going to a public cloud also has some challenges. Companies that use it give up a degree of control over their information and network security, which can make it inappropriate for some uses. Public clouds also usually have some form of usage-based pricing. This means that it can become expensive to migrate many applications and many users to an off-site provider.
A private cloud is one where the company controls the elements that compose its cloud. This cloud can still be scalable and flexible, but private clouds hit a hard limit when they fully utilize a company's existing infrastructure. If an application needs 80 processing cores and a company only has 60 available, the private cloud won't be able to scale to meet the need the way that a public cloud would. Related technologies like dedicated servers or virtualized servers have the same limitations as well. On the other hand, a private cloud can help to manage security concerns while also potentially limiting the ongoing usage-priced pricing issues that a public cloud brings.
The Hybrid Mindset
When a company chooses to adopt a hybrid cloud mindset for its IT, it opens itself up to the best of both worlds. When it uses a hybrid cloud, it gets the ability to mix and match public and private solutions to create a unique mix that suits its needs. For instance, a company could maintain security by running its most sensitive applications in-house but taking other applications and off-loading them to the cloud. This allows it to have the security it needs without having to maintain an over-sized data center. Another option that can help control costs while maintaining performance is to run applications in-house but to also have access to public cloud services during periods of peak load.
Hybrid clouds come from the decision to become a hybrid-cloud using company. With that decision, a company dedicates itself to looking at its IT problems and finding the right solution, regardless of what type of cloud needs to be utilized. This opens up the full spectrum of tools that the IT industry can offer, letting companies solve problems without limitations.